Method for selecting transport format combination guaranteed QoS in mobile communication system

ABSTRACT

The present invention relates to selecting a transport format combination (TFC) such that a quality of service (QoS) is guaranteed in a mobile communication system of a certain level even for a service having a low priority. The present invention selects a transport format combination such that not only a priority of each service is guaranteed but also a service quality is guaranteed by an MAC layer at the time of transporting services having different QoSs and different priorities.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Application No.2004-0044710, filed on Jun. 16, 2004, the contents of which is herebyincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a method for selecting a transportformat combination for transporting data proper to a channelcircumstance by a transmitting side medium access control (MAC) layer ina universal mobile telecommunication system (UMTS) and a Europeaninternational mobile telecommunication (IMT) 2000 system. The presentinvention relates, in particular, to a method for selecting a transportformat combination (TFC) such that a quality of service (QoS) isguaranteed in a mobile communication system of a certain level even fora service having a low priority.

BACKGROUND OF THE INVENTION

A universal mobile telecommunications system (UMTS) is athird-generation mobile communications system evolving from a globalsystem for mobile communications system (GSM), which is the Europeanstandard. The UMTS is aimed at providing enhanced mobile communicationsservices based on the GSM core network and wideband code-divisionmultiple-access (W-CDMA) technologies.

In December 1998, ETSI of Europe, ARIB/TTC of Japan, T1 of the UnitedStates, and TTA of Korea formed a Third Generation Partnership Project(3GPP) for creating detailed specifications of the UMTS technology.Within the 3GPP, in order to achieve rapid and efficient technicaldevelopment of the UMTS, five technical specification groups (TSG) havebeen created for determining the specification of the UMTS byconsidering the independent nature of the network elements and theiroperations.

Each TSG develops, approves, and manages the specification within arelated region. Among these groups, the radio access network (RAN) group(TSG-RAN) develops the specifications for the functions, requirements,and interface of the UMTS terrestrial radio access network (UTRAN),which is a new radio access network for supporting W-CDMA accesstechnology in the UMTS.

A related art UMTS network structure 1 is illustrated in FIG. 1. Asshown, a mobile terminal, or user equipment (UE) 2 is connected to acore network (CN) 4 through a UMTS terrestrial radio access network(UTRAN) 6. The UTRAN 6 configures, maintains and manages a radio accessbearer for communications between the UE 2 and the core network 4 tomeet end-to-end quality of service requirements.

The UTRAN 6 includes at least one radio network subsystem (RNS) 8, eachof which comprises one radio network controller (RNC) 10 for a pluralitybase stations, or Node Bs 12. The RNC 10 connected to a given basestation 12 is the controlling RNC for allocating and managing the commonresources provided for any number of UEs 2 operating in one cell. One ormore cells exist in one Node B. The controlling RNC 10 controls trafficload, cell congestion, and the acceptance of new radio links. Each NodeB 12 may receive an uplink signal from a UE 2 and may transmit adownlink signals to the UE 2. Each Node B 12 serves as an access pointenabling a UE 2 to connect to the UTRAN 6, while an RNC 10 serves as anaccess point for connecting the corresponding Node Bs to the corenetwork 4.

Among the radio network subsystems 8 of the UTRAN 6, the serving RNC 10is the RNC managing dedicated radio resources for the provision ofservices to a specific UE 2 and is the access point to the core network4 for data transfer to the specific UE. All other RNCs 10 connected tothe UE 2 are drift RNCs, such that there is only one serving RNCconnecting the UE to the core network 4 via the UTRAN 6. The drift RNCs10 facilitate the routing of user data and allocate codes as commonresources.

The interface between the UE 2 and the UTRAN 6 is realized through aradio interface protocol established in accordance with radio accessnetwork specifications describing a physical layer (L1), a data linklayer (L2) and a network layer (L3) described in, for example, 3GPPspecifications. These layers are based on the lower three layers of anopen system interconnection (OSI) model that is well known incommunications systems.

A related art architecture of the radio interface protocol isillustrated in FIG. 2. As shown, the radio interface protocol is dividedhorizontally into a physical layer, a data link layer, and a networklayer, and is divided vertically into a user plane for carrying datatraffic such as voice signals and Internet protocol packet transmissionsand a control plane for carrying control information for the maintenanceand management of the interface. The radio interface protocols areprovided in the UE and the UTRAN as a pair, and transmit data within aradio period. Each radio interface protocol layer will be explained.

A first layer, a physical layer (PHY) transmits data to a radio periodby using various radio transport techniques. Specifically, the physicallayer (PHY) provides information transfer service to a higher layer andis linked via a transport channel (TrCH) to a medium access control(MAC) layer. Through the transport channel (TrCH), data of a wire periodis transported reliably between the PHY layer and the MAC layer. Thetransport channel is divided into a dedicated transport channel and acommon transport channel depending on whether a channel is shared. Also,data transmission is performed through a physical channel betweendifferent physical layers, namely, between physical layers of a sendingside (transmitter) and a receiving side (receiver).

The second layer includes a MAC layer, a radio link control (RLC) layer,a broadcast/multicast control (BMC) layer and a packet data convergenceprotocol (PDCP) layer. The MAC layer maps various logical channels(LoCH) to various transport channels. The MAC layer also multiplexeslogical channels by mapping several logical channels to one transportchannel. The MAC layer is connected to an upper RLC layer via thelogical channel. The logical channel can be divided into a controlchannel for transmitting control plane information a traffic channel fortransmitting user plane information according to the type of informationtransmitted.

The MAC layer is divided into a MAC-b sublayer, a MAC-d sublayer, aMAC-c/sh sublayer, a MAC-hs sublayer and a MAC-e sublayer according tothe type of transport channel being managed. The MAC-b sublayer managesa broadcast channel (BCH), which is a transport channel handling thebroadcast of system information. The MAC-c/sh sublayer manages commontransport channels such as an FACH (Forward Access Channel) or a DSCH(Downlink Shared Channel) that is shared by other terminals. The MAC-dsublayer handles the managing of a DCH (Dedicated Channel), namely, adedicated transport channel for a specific terminal. In order to supportuplink and downlink high speed data transmissions, the MAC-hs sublayermanages an HS-DSCH (High Speed Downlink Shared Channel), namely, atransport channel for high speed downlink data transmission, and theMAC-e sublayer manages an E-DCH (Enhanced Dedicated Channel), namely, atransport channel for high speed uplink data transmissions.

The RLC layer guarantees a quality of service (QoS) of each radio bearer(RB) and handles the transmission of corresponding data. The RLC layerincludes one or two independent RLC entities for each RB in order toguarantee a particular QoS of each RB. The RLC layer also provides threeRLC modes, namely, a Transparent Mode (TM, an Unacknowledged Mode (UM)and an Acknowledged Mode (AM), to support various types of QoS. Also,the RLC controls the size of data to be suitable for a lower layer intransmitting over a radio interface. For this purpose, the RLC segmentsand concatenates the data received from the upper layer.

A PDCP (Packet Data Convergence Protocol) layer is a higher layer of theRLC layer and allows the data transmitted through a network protocol(such as an IPv4 or IPv6) to be effectively transmitted over a radiointerface with a relatively small bandwidth. To achieve this, the PDCPlayer performs a header compression function wherein only necessaryinformation is transmitted in a header part of the data to therebyincrease transmission efficiency over the radio interface. Because thePDCP layer performs the header compression as a basic function, itexists only at a packet switched (PS) domain. One PDCP entity isprovided per RB to provide an effective header compression function withrespect to each PS service.

A BMC (Broadcast/Multicast Control) layer, located at an upper portionof the RLC layer in the second layer (L2), schedules a cell broadcastmessage and broadcasts the message to terminals located in a specificcell.

A radio resource control (RRC) layer located at the lowest portion ofthe third layer (L3) is defined in the control plane and controls theparameters of the first and second layers with respect to theestablishment, reconfiguration and release of RBs. The RRC layer alsocontrols logical channels, transport channels and physical channels.Here, the RB refers to a logical path provided by the first and secondlayers of the radio protocol for data transmission between the terminaland the UTRAN. In general, the establishment of the RB refers tostipulating the characteristics of a protocol layer and a channelrequired for providing a specific data service, and setting theirrespective detailed parameters and operation methods.

Hereinafter, a method for selecting a transport format combination (TFC)performed by the MAC layer will be explained. The TFC selection is forselecting a transport block (TB) of a suitable size and the number ofthe TBs according to a wireless channel circumstance momentarily changedto thereby efficiently utilize a limited radio resource. The MAC layertransports transport blocks (TBs) to the PHY layer through a transportchannel. A transport format (TF) is a definition for a TB size and thenumber of TBs to be transported by one transport channel. At the time ofdetermining TFs for a specific transport channel, the MAC layerconsiders transport channel multiplexing in the PHY layer.

Transport channel multiplexing is for mapping plural transport channelsinto one coded composite transport channel (CCTrCH). Even if the PHYlayer performs the transport channel multiplexing, the MAC layerconsiders every transport channel mapped into the same CCTrCH at thetime of determining TFs. Since an amount of data processed by the PHYlayer is an amount of data transported through the CCTrCH, the MAC layerdetermines TFs of each transport channel in consideration to the CCTrCH.

Presently, a combination of TFs is known as a transport formatcombination (TFC). The TFC is not determined by the MAC layer itself,but rather is selected from a set of available traffic flow templates(TFTS) indicated by the RRC layer of the UTRAN. That is, the RRC layerof the UTRAN informs the MAC layer of a set of available TFCs for oneCCTrCH at the time of an initial RB setting, and the MAC layer selects aproper TFC from a set of available TFCs (TFCS) within each transmissiontime interval (TTI). A terminal RRC receives TFCS information from aUTRAN RRC via an air interface, and informs a terminal MAC layer of thereceived TFCS information.

The main function of the MAC layer is for selecting an optimum TFC in aTFCS within each TTI. The optimum TFC selection is divided into twosteps. First, a valid TFCS is constructed in a TFCS allocated to theCCTrCH. Then, the optimum TFC is selected in the valid TFCS. The validTFCS is a set of available TFs at a corresponding TTI in a preset TFCS,which is formed because a radio channel circumstance is momentarilychanged and thereby a maximum transmission power of a terminal ischanged. Since an amount of transmittable data is generally proportionalto a size of transmission power, available TFCs are limited by themaximum transmission power.

An optimum TFC indicates a TFC that can optimally transmit data to betransmitted in a valid TFCS limited by the maximum transmission power.The optimum TFC is selected in a valid TFCS on the basis of a logicalchannel priority, not on the basis of a data transmission amount. Eightpriorities, 1 to 8, with 1 being the highest priority, are set to alogical channel. In case that plural logical channels are multiplexed toone transport channel and plural transport channels are multiplexed toone CCTrCH, the MAC layer selects a TFC that can optimally transmitlogical channel data having a high priority.

FIG. 3 illustrates a general method for selecting a TFC. FIG. 4illustrates a structure wherein plural logical channels and pluraltransport channels are multiplexed to one CCTrCH. The process forselecting a TFC by the MAC layer will be explained with reference toFIG. 4. FIG. 4 illustrates a case wherein three logical channels (LoCH)and two transport channels (TrCH) are mapped into the CCTrCH. It furtherillustrates a case where a LoCH1 and a LoCH2 are multiplexed to theTrCH1. Here, the LoCH1 has a priority of 1, the LoCH2 has a priority of5, and the LoCH3 has a priority of 3. Accordingly, the LoCH1 has thehighest priority.

The MAC layer selects an optimum TFC in a preset TFCS within each TTI.As shown in FIG. 4, the TFCS is not determined by the MAC layer but istransmitted to the MAC layer from the RRC when the RRC configures an RB.In FIG. 4, 16 TFCs are defined, each TFC having an identification numbercalled a TFC index. The numbers inside the round bracket (x, y)originally indicated the number of TBs of the TrCH1 having a size 1 andthe number of TBs of the TrCH2 having a size 2, respectively. However,in the present invention, the size of every TB is preferably equal toeach other. Thus, the numbers inside the round bracket denote the numberof TBs of the TrCH1 and the number of TBs of the TrCH2.

Referring to FIG. 4, it is assumed that each Tx Buffer 1, Tx Buffer 2,and Tx Buffer 3 of the RLC respectively have 3, 4, and 2 data blocks(TB) that are in a transmission waiting state. Furthermore, it isassumed that a maximum 10 TBs can be transmitted by a limited maximumtransmission power. Under this state, the MAC layer selects an optimumTFC (TFCI=11) by a method illustrated in FIG. 5.

The method for selecting an optimum TFC illustrated in FIG. 5 will beexplained in more detail with reference to FIG. 3. Referring to FIG. 5,when 16 TFCs are provided (1), a maximum 10 TBs can be transmitted by alimited transmission power. Accordingly, the MAC layer configures avalid TFCS excluding TFCI=13 and TFCI=15 in a given TFCS (2) (S11).TFCI=13 and TFCI=15 are excluded because the sum of their respective TBson TrCH1 and TrCH2 exceeds 10 TBs. For example, for TFCI=13, there are 6TBs present on TrCH1 and 6 TBs present on TrCH2. Therefore, the sum ofthe TBs on TrCH1 and TrCH2 equals 12. 12 exceeds the maximum number ofTBs that can be transmitted 10. Thus, the MAC layer excludes TFCI=13when configuring the valid TFCS (2).

In the valid TFCS, the MAC layer excludes a TFC which transmits more TBsthan the total number of TBs stored in the Tx buffer of the RLC at eachtransport channel. The reason for excluding a TFC greater than a dataamount of the transport channel is as follows. If a TFC greater than adata amount of the transport channel is selected, the RLC must generatea TB comprised of only a padding without data, thus causing a waste ofradio resources.

Referring to FIG. 4, the TrCH1 has a total 7 TBs resulting from the sumof the TBs stored in the Tx buffer 1 (3 TBs) and Tx buffer 2 (4 TBs).These TBs are transmitted to the TrCH1 via the LoCH1 and the LoCH2,respectively. Accordingly, the MAC layer excludes TFCI=14 because thenumber of TBs for TrCH1 of TFCI=14 equals 8. Because 8 exceeds the totalnumber of TBs for TrCH1 of FIG. 4 (7 TBs), TFCI=14 is excluded.Likewise, because the TrCH2 of FIG. 4 has 2 TBs, the MAC layer excludesthe TFCI=9 and TFCI=12 because their number of TBs for TrCH2, 4 TBs and4 TBs, respectively exceeds 2 TBs. The MAC layer then goes on toconfigure a new valid TFCS excluding the TFCI=9, 12, and 14 (3) (S12).

Because the LoCH1 has the highest priority of 1, the MAC layerconfigures a new valid TFCS on the basis of the LoCH1. Since the LoCH1has three TBs, the MAC layer selects TFCs which can optimally transmitthe data of the LoCH1. Here, the MAC layer selects the TFCI=6, 7, 8, 10,and 11 because the number of TBs for TrCH1 of each TFCI is greater than3. Accordingly, a new valid TFCS (4) is configured excluding TFCI=0, 1,2, 3, 4, and 5 of step (3) (S13).

Subsequently, the MAC layer configures a new valid TFCS on the basis ofthe LoCH3 having the next highest priority. Since the LoCH3 has two TBs,the MAC layer selects TFCs which can optimally transmit the data of theLoCH3. Here, the MAC layer selects the TFCI=8 and the TFCI=11 becausethe number of TBs for TrCH2 of each TFCI is equal to or greater than 2.Thus, a new valid TFCS (5) is configured excluding TFCI=6, 7, and 10 ofstep (4).

Furthermore, the MAC layer configures a new valid TFCS on the basis ofthe LoCH2 having the next highest priority. Since the LoCH2 has threeTBs, the MAC layer selects the TFC which can optimally transmit the dataof the LoCH2. Here, the MAC layer selects the TFCI=11 because it has thegreatest number of TBs for TrCH1 among the TFCIs left in the valid TFCS(5). Accordingly, a new valid TFCS (6) is configured excluding TFCI=8 ofstep (5) (S13-S14).

If there is a logical channel not constituting the valid TFCS, that is,a logical channel not included in the valid TFCS (S15), the MAC layerperforms the step (4). However, if there is no logical channel notincluded in the valid TFCS, the MAC layer selects an arbitrary TFCwithin the configured valid TFCS as an optimum TFC (S16). Here, becausethere is only one TFC in the valid TFCS, the TFCI=11 is selected as theoptimum TFC (6). Eventually, the number of TBs to be transmitted to eachlogical channel within the TTI are LoCH1=3, LoCH2=3, and LoCH3=2.

For reference, the order of the steps 2 and 3 in the above method may beinterchanged.

In a conventional method for selecting a transport format combination,the MAC layer selects a TFC on the basis of a priority of a logicalchannel. That is, a TFC that can optimally transmit data of a logicalchannel having the highest priority is selected. However, data of alogical channel having a low priority may not be transmitted at all.

Referring to FIG. 4, the above problem will be explained. If the LoCH1having the highest priority has 7 TBs, the MAC layer selects theTFCI=14=(8,0) by the method of FIG. 5. Accordingly, each logical channelhas the following number of TBs to be transmitted within the TTI(LoCH1=7, LoCH2=1, and LoCH3=0), which is shown in FIG. 6.

A situation where data can not be transmitted due to a transmission ofdata of a logical channel having a higher priority despite there beingtransmittable data is referred to as starvation. As long as a TFC isselected on the basis of an absolute priority of a logical channel likein a general TFT selection method, starvation may occur.

Starvation significantly lowers the quality of a specific service. Forexample, for a real-time packet service such as audio streaming, acertain amount of data has to be continuously transmitted. However, ifstarvation occurs due to a priority of a logical channel, packets thathave not been transmitted for a long time are no longer required and arediscarded, thereby lowering the quality of service.

SUMMARY OF THE INVENTION

The present invention is directed to a method for selecting a transportformat combination (TFC) such that a quality of service (QoS) isguaranteed in a mobile communication system even for a service having alow priority by selecting a transport format combination that guaranteesnot only a priority of each service but also a quality of service by aMAC layer at the time of transporting services having different QoSs anddifferent priorities.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the presentinvention is embodied in a method for selecting a transport formatcombination for transmitting a plurality of data units within atransmission time interval by multiplexing data units from a pluralityof upper layer channels to a lower layer channel, the transport formatcombination selected from a determined transport format combination setand a transmission priority exists for transmitting the data units fromeach of the plurality of upper layer channels, wherein at least one ofthe plurality of upper layer channels has an associated minimum qualityof service (QoS) requirement and the transport format combination isselected such that the minimum quality of service (QoS) for the at leastone upper layer channel is guaranteed. Preferably, the plurality ofupper layer channels are logical channels and the lower layer channel isa coded composite transport channel.

In one aspect of the present invention, the transport format combinationis selected by considering the minimum quality of service (QoS)requirement of the at least one upper layer channel before consideringthe transmission priority of the plurality of upper layer channels. Themultiplexing may be performed at the lower layer. The multiplexing maybe performed at a medium access control (MAC) layer.

In another aspect of the present invention, the minimum quality ofservice (QoS) comprises at least one of a minimum bit rate, a guaranteedbit rate and a minimum transfer delay. The minimum quality of service(QoS) is guaranteed by the transport format combination set determinedat a radio resource control layer. However, the minimum quality ofservice (QoS) may be guaranteed by selection of the transport formatcombination at a medium access control (MAC) layer. Preferably, thetransport format combination is selected by considering the minimum QoSrequirement of the at least one upper layer channel before consideringthe transmission priority of the plurality of upper layer channels onlyif data units are to be transmitted over the at least one logicalchanne.

Preferably, the plurality of upper layer channels and the lower layerchannel are in a UTRAN. Alternatively, the plurality of upper layerchannels and the lower layer channel are in a mobile terminal, whereinthe minimum quality of service (QoS) is guaranteed by a transport formatcombination set determined at a radio resource control layer of a UTRAN.

In another embodiment of the present invention, a method fortransmitting a plurality of data units within a transmission timeinterval by multiplexing data units from a plurality of upper layerchannels to a lower layer channel, the plurality of upper layer channelseach having a different transmission priority for transmitting the dataunits comprises determining whether at least one of the plurality ofupper layer channels has an associated minimum quality of service (QoS)requirement, and if at least one of the plurality of upper layerchannels has an associated minimum QoS requirement, selecting atransport format combination from a determined transport formatcombination set such that the minimum QoS for the at least one upperlayer channel is guaranteed.

In one aspect of the present invention, the minimum QoS is guaranteed bythe transport format combination set determined at a radio resourcecontrol layer. Otherwise, the minimum QoS is guaranteed by selection ofthe transport format combination at a medium access control (MAC) layer.

In another aspect of the present invention, the method further comprisesdetermining whether any data units are to be transmitted over the atleast one upper layer channel having an associated minimum quality ofservice (QoS) requirement, wherein the transport format combination isselected by considering the minimum QoS requirement of the at least oneupper layer channel before considering the transmission priority of theplurality of upper layer channels only if data units are to betransmitted over the at least one upper layer channel.

Preferably, the plurality of upper layer channels are logical channelsand the lower layer channel is a coded composite transport channel. Themultiplexing is performed at the lower layer. Preferably, themultiplexing is performed at a medium access control (MAC) layer.

The minimum quality of service (QoS) comprises at least one of a minimumbit rate, a guaranteed bit rate and a minimum transfer delay. Theplurality of upper layer channels and the lower layer channel are in aUTRAN. Alternatively, the plurality of upper layer channels and thelower layer channel are in a mobile terminal, wherein the minimum QoS isguaranteed by a transport format combination set determined at a radioresource control layer of a UTRAN.

In another embodiment of the present invention, a mobile communicationdevice for transmitting a plurality of data units within a transmissiontime interval comprises an RF module, an antenna, a storage unit adaptedto store the data and the control information, a display adapted toconvey information to the user, and a processing unit adapted to selecta transport format combination for transmitting the plurality of dataunits within a transmission time interval by multiplexing data unitsfrom a plurality of upper layer channels to a lower layer channel, thetransport format combination selected from a determined transport formatcombination set and a transmission priority exists for transmitting thedata units from each of the plurality of upper layer channels, whereinat least one of the plurality of upper layer channels has an associatedminimum quality of service (QoS) requirement and the transport formatcombination is selected such that the minimum quality of service (QoS)for the at least one upper layer channel is guaranteed.

In another embodiment of the present invention, a network for providinga service to a mobile terminal comprises a transmitter adapted totransmit data and a control information indicator to the mobile terminalvia a first channel and to transmit control information to the mobileterminal via a second channel, a receiver adapted to receive informationfrom the mobile terminal, and a controller adapted to select a transportformat combination for transmitting a plurality of data units within atransmission time interval by multiplexing data units from a pluralityof upper layer channels to a lower layer channel, the transport formatcombination selected from a determined transport format combination setand a transmission priority exists for transmitting the data units fromeach of the plurality of upper layer channels, wherein at least one ofthe plurality of upper layer channels has an associated minimum qualityof service (QoS) requirement and the transport format combination isselected such that the minimum quality of service (QoS) for the at leastone upper layer channel is guaranteed.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. Features, elements, and aspects of the invention that arereferenced by the same numerals in different figures represent the same,equivalent, or similar features, elements, or aspects in accordance withone or more embodiments.

FIG. 1 illustrates a general UMTS network structure.

FIG. 2 illustrates a general radio interface protocol architecture usedin the UMTS.

FIG. 3 illustrates a method for selecting a transport format combinationby a MAC layer.

FIG. 4 illustrates a plurality of logical channels and a plurality oftransport channels multiplexed into one radio channel.

FIG. 5 illustrates a method for selecting a transport format combinationwhen a number of transport blocks of a logical channel having highestpriority is 3.

FIG. 6 illustrates a method for selecting a transport format combinationwhen a number of transport blocks of a logical channel having highestpriority is 7.

FIG. 7 illustrates a method for configuring a transport formatcombination set guaranteed a minimum QoS of a specific logical channelby an upper layer in accordance with one embodiment of the presentinvention.

FIG. 8 illustrates a method for selecting an optimum transport formatcombination when a number of transport blocks of a logical channelhaving highest priority is 3 in a transport format combination set ofFIG. 7.

FIG. 9 illustrates a method for selecting an optimum transport formatcombination when a number of transport blocks of a logical channelhaving highest priority is 7 in a transport format combination set ofFIG. 7.

FIG. 10 illustrates a method for indicating a guarantee of a minimum QoSof a specific logical channel to an MAC layer by an upper layer inaccordance with one embodiment of the present invention.

FIG. 11 illustrates a method for selecting an optimum transport formatcombination when a number of transport blocks of a logical channelhaving highest priority is 3 according to the indication for a guaranteeof a minimum QoS by the upper layer in accordance with one embodiment ofthe present invention.

FIG. 12 illustrates a method for selecting an optimum transport formatcombination when a number of transport blocks of a logical channelhaving highest priority is 7 according to the indication for a guaranteeof a minimum QoS by the upper layer in accordance with one embodiment ofthe present invention.

FIG. 13 illustrates a method for selecting a transport formatcombination guaranteed a minimum QoS by an MAC layer in accordance withone embodiment of the present invention.

FIG. 14 illustrates a terminal for selecting a transport formatcombination guaranteed a minimum QoS by an MAC layer in accordance withone embodiment of the present invention.

FIG. 15 illustrates a network for selecting a transport formatcombination guaranteed a minimum QoS by an MAC layer in accordance withone embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

The present invention relates to a method for selecting a transportformat combination capable of preventing a specific service having a lowpriority from causing a starvation when selecting an optimum TFC by aMAC layer when the specific service requires a minimum QoS. The methodincludes the following two methods: a first method for configuring aTFCS by considering a minimum QoS of a specific service and a secondmethod for selecting a TFCS by considering a minimum QoS of a specificservice.

The first method is for configuring a TFCS that can guarantee a QoS whena specific service requires a minimum QoS when configuring an RB for thespecific service by an RRC layer. The minimum QoS includes a minimum bitrate and a minimum delay, which is a characteristic required for areal-time service such as voice or streaming data. The RRC layerconfigures a TFCS that can guarantee a minimum QoS and configures a newTFCS whenever an RB for a specific service is initially configured orwhenever the RB is re-configured during a data transmission, such aswhen a mapping structure of a logical channel or a transport channel ischanged in order to transmit the new TFCS to a MAC layer, for example.

According to the present invention, when a new audio streaming serviceis to be provided to an LoCH3 under a state that an LoCH1 and an LoCH2provide an interactive type service such as web browsing, the RRCconfigures a TFCS by considering a minimum QoS of the audio streamingservice. If the required minimum QoS of the audio streaming service isto transmit at least one TB within each TTI, the RRC configures a TFCS,as shown in FIG. 7. The TFCS shown in FIG. 7 is a TFCS exclusivelyconstituted with TFCs that can transmit at least one TB.

FIG. 8 illustrates a method for selecting an optimum TFC when a numberof TBs for LoCH1 is 3 in FIG. 7. FIG. 9 illustrates a method forselecting an optimum TFC when a number of TBs for the LoCH1 is 7 in FIG.7.

Referring to FIG. 7, in a case where a TFCS excludes a TFC having zeronumber of TBs for TrCH2, the MAC layer selects a TFCI=6=(6, 2) when a TBof the LoCH1 is 3 by the method illustrated in FIG. 8. The MAC layeralso selects a TFCI=6=(6, 2) when a TB of the LoCH1 is 7 by the methodillustrated in FIG. 9. Accordingly, the LoCH3 can continuously transmitdata without starvation.

However, the first method has the following characteristics. First, adata transmission is influenced by a radio channel circumstance and maybe stopped in some cases. The state that the data transmission isstopped is referred to as a blocked state. At the time of the blockedstate, a TFCI=0=(0, . . . , 0) having an empty TFC is selected to stopthe data transmission since a MaxPower has no TB (MaxPower=0 TB).However, since no empty TFC exists in the present invention according tothe first method, no valuable TFC exists in a valid TFCS of step (2) ofFIG. 8 and thereby a protocol error may be caused.

Second, even if a logical channel requires a minimum QoS, there may beno data to transmit. In this case, the MAC layer selects a TFC that cantransmit at least one TB by the first method. Accordingly, the RLCgenerates a padding block or a protocol error may be caused. Thiscorresponds to the case where the LoCH3 in FIG. 7 has 0 TB. If the LoCH3has 0 TB, then no valuable TFC exists in a valid TFCS of step (5) ofFIG. 8 and thereby a protocol error is caused.

Third, a new TFCS has to be constructed whenever an RB is configured orre-configured, so that wireless signaling overhead is increased. Thereason is as follows. The TFCS is basically configured by a UTRAN RRClayer, and a terminal receives the configured TFCS wirelessly. If theTFCS is re-constructed whenever an RB is configured or re-configured,TFCS information has to be transmitted wirelessly at each moment therebyincreasing signaling overhead.

The second method for selecting a TFCS by considering a more improvedminimum QoS according to the present invention will now be explained.The second method has the same TFCS configuration as the first method,but is different from the first method in that a MAC layer selects anoptimum TFC by considering a minimum QoS before a priority of acorresponding logical channel thereof. The second method providesindication information for guaranteeing a minimum QoS of a specificlogical channel to the MAC layer by an upper layer such as an RRC layeror a RLC layer. The second method will be explained with reference toFIG. 10.

FIG. 10 illustrates a structure of a protocol layer for indicating aguarantee of a minimum QoS of a specific logical channel to an MAC layerby an upper layer such as an RRC layer or an RLC layer according to thepresent invention. FIG. 11 illustrates a method for selecting an optimumTFC when a number of TBs for LoCH1 is 3 in FIG. 10. FIG. 12 illustratesa method for selecting an optimum TFC when a number of TBs for the LoCH1is 7 in FIG. 10. FIG. 13 illustrates a method for selecting a TFCguaranteed a minimum QoS according to the present invention. Whencompared with the general TFT selection method, the present inventionfurther comprises a method for configuring a TFCS by considering aminimum QoS for a specific logical channel (S23-S29 of FIG. 13).

As shown in FIG. 10, when an upper layer, such as an RRC layer transmitsan indication for guaranteeing a minimum QoS=1 TB/TTI for the LoCH3 tothe MAC layer, the MAC layer selects a TFCI=6=(6, 2) when a number ofTBs of the LoCH1 is 3 by the method illustrated in FIG. 13. The MAClayer also selects a TFCI=6=(6, 2) when a number of TBs of the LoCH1 is7 by the method illustrated in FIG. 12. Accordingly, the LoCH3 cancontinuously transmit data without starvation in any case as in thefirst method.

The second method will be explained in more detail with reference toFIG. 11. The MAC layer configures a valid TFCS (2) by excluding TFCswhich exceed a maximum transmission power (MaxPower) from the TFCS (1).Preferably, the MAC configures a valid TFCS by excluding from the setTFCS a TFC wherein the sum of a number of TBs of a TrCH1 and a number ofTBs of a TrCH2 exceeds 10 TB (the number of transmittable TBs in case ofa MaxPower).

Subsequently, the MAC layer configures a valid TFCS (3) of FIG. 11 byexcluding a TFC which transmits more TBs than the total number of TBsstored in the Tx buffer of the upper layer at each transport channel(S22 of FIG. 13).

When the MAC layer has received an indication for guaranteeing a minimumQoS for a specific logical channel from the RRC layer, that is, when alogical channel of which minimum QoS is to be guaranteed exists (S23 ofFIG. 13), the MAC layer selects a logical channel having the highestpriority among logical channels that have not configured a TFCS QoSguaranteed for the specific logical channel (S24 of FIG. 13) and thenchecks the amount of data to be transmitted via the selected logicalchannel (S25 of FIG. 13).

As shown in FIG. 10, since a logical channel to be guaranteed a minimumQoS is the LoCH3, the MAC layer selects the LoCH3 and then compares thedata amount to be transmitted via the selected LoCH3 with the minimumQoS=1 TB/TTI. If the amount of data to be transmitted via the selectedLoCH3 is not less than the minimum QoS=1 TB/TTI, the MAC layerconfigures a QoS guaranteed TFCS by excluding from the valid TFCS a TFCthat cannot guarantee the minimum QoS of the LoCH3 (S26 of FIG. 13; (4)of FIG. 11; and (4) of FIG. 12).

However, if the amount of data to be transmitted via the selected LoCH3is less than the minimum QoS=1 TB/TTI, the MAC layer configures a QoSguaranteed TFCS by excluding from the valid TFCS a TFC that can notguarantee a data transmission of the LoCH3 (S27 of FIG. 13).

If there is a logical channel not included in the QoS guaranteed TFCS,the MAC layer returns to the step of S24 of FIG. 13. However, if thereis not a logical channel not included in the QoS guaranteed TFCS, theMAC layer configures the QoS guaranteed TFCS as a valid TFCS (S29 ofFIG. 13). The subsequent processes are the same as those of the generalTFC selection method, as shown in FIG. 3.

More specifically, if a QoS guaranteed TFCS is configured by consideringonly a minimum QoS irrespective of the amount of data to be transmittedvia a logical channel according to the second method of the presentinvention, the second problem of the first method of the presentinvention is caused, whereby the RLC layer generates a padding block ora protocol error is generated when data to be transmitted does notexist. Accordingly, even if a logical channel has a defined minimum QoS,the amount of data of the corresponding logical channel must also beconsidered when configuring a QoS guaranteed TFCS as shown in step ofS25 of FIG. 13.

In the present invention, a service quality of a certain level isguaranteed even in service having a low priority by selecting atransport format combination wherein not only a priority of each serviceis considered but also a service quality is considered by an MAC layerwhen transporting services having different QoSs and differentpriorities by multiplexing.

In the present invention, the MAC layer selects a TFC by considering anamount of data to be transmitted via a logical channel with a minimumQoS guaranteed, thereby preventing generation of a padding block or aprotocol error.

Referring to FIG. 14, a block diagram of a mobile communication device400 of the present invention is illustrated, for example a mobile phonefor performing the methods of the present invention. The mobilecommunication device 400 includes a processing unit 410 such as amicroprocessor or digital signal processor, an RF module 435, a powermanagement module 406, an antenna 440, a battery 455, a display 115, akeypad 420, a storage unit 430 such as flash memory, ROM or SRAM, aspeaker 445 and a microphone 450.

A user enters instructional information, such as a telephone number, forexample, by pushing the buttons of a keypad 420 or by voice activationusing the microphone 450. The processing unit 410 receives and processesthe instructional information to perform the appropriate function, suchas to dial the telephone number. Operational data may be retrieved fromthe storage unit 430 to perform the function. Furthermore, theprocessing unit 410 may display the instructional and operationalinformation on the display 415 for the user's reference and convenience.

The processing unit 410 issues instructional information to the RFmodule 435, to initiate communication, for example, transmit radiosignals comprising voice communication data. The RF module 435 comprisesa receiver and a transmitter to receive and transmit radio signals. Theantenna 440 facilitates the transmission and reception of radio signals.Upon receiving radio signals, the RF module 435 may forward and convertthe signals to baseband frequency for processing by the processing unit410. The processed signals would be transformed into audible or readableinformation outputted via the speaker 445, for example.

The processing unit 410 is adapted to store message history data ofmessages received from and messages transmitted to other users in thestorage unit 430, receive a conditional request for message history datainput by the user, process the conditional request to read messagehistory data corresponding to the conditional request from the storageunit, and output the message history data to the display unit 415. Thestorage unit 430 is adapted to store message history data of thereceived messages and the transmitted messages.

FIG. 15 illustrates a block diagram of a UTRAN 520 according to thepreferred embodiment of the present invention. The UTRAN 520 includesone or more radio network sub-systems (RNS) 525. Each RNS 525 includes aradio network controller (RNC) 523 and a plurality of Node-Bs (basestations) 521 managed by the RNC. The RNC 523 handles the assignment andmanagement of radio resources and operates as an access point withrespect to the core network 4. Furthermore, the RNC 523 is adapted toperform the methods of the present invention.

The Node-Bs 521 receive information sent by the physical layer of theterminal 400 through an uplink, and transmit data to the terminalthrough a downlink. The Node-Bs 521 operate as access points, or as atransmitter and receiver, of the UTRAN 520 for the terminal 400. It willbe apparent to one skilled in the art that the mobile communicationdevice 400 may be readily implemented using, for example, the processingunit 410 or other data or digital processing device, either alone or incombination with external support logic.

By utilizing the present invention, the user of a mobile communicationdevice may select a transport format combination for transmitting aplurality of data units within a transmission time interval bymultiplexing data units from a plurality of upper layer channels to alower layer channel, the transport format combination selected from adetermined transport format combination set and a transmission priorityexists for transmitting the data units from each of the plurality ofupper layer channels, wherein at least one of the plurality of upperlayer channels has an associated minimum quality of service (QoS)requirement and the transport format combination is selected such thatthe minimum quality of service (QoS) for the at least one upper layerchannel is guaranteed.

Although the present invention is described in the context of mobilecommunication, the present invention may also be used in any wirelesscommunication systems using mobile devices, such as PDAs and laptopcomputers equipped with wireless communication capabilities. Moreover,the use of certain terms to describe the present invention should notlimit the scope of the present invention to certain type of wirelesscommunication system, such as UMTS. The present invention is alsoapplicable to other wireless communication systems using different airinterfaces and/or physical layers, for example, TDMA, CDMA, FDMA, WCDMA,etc.

The preferred embodiments may be implemented as a method, apparatus orarticle of manufacture using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. The term “article of manufacture” as used herein refers to codeor logic implemented in hardware logic (e.g., an integrated circuitchip, Field Programmable Gate Array (FPGA), Application SpecificIntegrated Circuit (ASIC), etc.) or a computer readable medium (e.g.,magnetic storage medium (e.g., hard disk drives, floppy disks, tape,etc.), optical storage (CD-ROMs, optical disks, etc.), volatile andnon-volatile memory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs,SRAMs, firmware, programmable logic, etc.).

Code in the computer readable medium is accessed and executed by aprocessor. The code in which preferred embodiments are implemented mayfurther be accessible through a transmission media or from a file serverover a network. In such cases, the article of manufacture in which thecode is implemented may comprise a transmission media, such as a networktransmission line, wireless transmission media, signals propagatingthrough space, radio waves, infrared signals, etc. Of course, thoseskilled in the art will recognize that many modifications may be made tothis configuration without departing from the scope of the presentinvention, and that the article of manufacture may comprise anyinformation bearing medium known in the art.

The logic implementation shown in the figures described specificoperations as occurring in a particular order. In alternativeimplementations, certain of the logic operations may be performed in adifferent order, modified or removed and still implement preferredembodiments of the present invention. Moreover, steps may be added tothe above described logic and still conform to implementations of theinvention.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

1. A method for selecting a transport format combination fortransmitting a plurality of data units within a transmission timeinterval by multiplexing data units from a plurality of upper layerchannels to a lower layer channel, the transport format combinationselected from a determined transport format combination set and atransmission priority exists for transmitting the data units from eachof the plurality of upper layer channels, wherein at least one of theplurality of upper layer channels has an associated minimum quality ofservice (QoS) requirement and the transport format combination isselected such that the minimum quality of service (QoS) for the at leastone upper layer channel is guaranteed.
 2. The method of claim 1, whereinthe plurality of upper layer channels are logical channels and the lowerlayer channel is a coded composite transport channel.
 3. The method ofclaim 1, wherein the transport format combination is selected byconsidering the minimum quality of service (QoS) requirement of the atleast one upper layer channel before considering the transmissionpriority of the plurality of upper layer channels.
 4. The method ofclaim 1, wherein the multiplexing is performed at the lower layer. 5.The method of claim 1, wherein the multiplexing is performed at a mediumaccess control (MAC) layer.
 6. The method of claim 1, wherein theminimum quality of service (QoS) comprises at least one of a minimum bitrate, a guaranteed bit rate and a minimum transfer delay.
 7. The methodof claim 1, wherein the minimum quality of service (QoS) is guaranteedby the transport format combination set determined at a radio resourcecontrol layer.
 8. The method of claim 1, wherein the minimum quality ofservice (QoS) is guaranteed by selection of the transport formatcombination at a medium access control (MAC) layer.
 9. The method ofclaim 8, wherein the transport format combination is selected byconsidering the minimum QoS requirement of the at least one upper layerchannel before considering the transmission priority of the plurality ofupper layer channels only if data units are to be transmitted over theat least one logical channel.
 10. The method of claim 1, wherein theplurality of upper layer channels and the lower layer channel are in aUTRAN.
 11. The method of claim 1, wherein the plurality of upper layerchannels and the lower layer channel are in a mobile terminal.
 12. Themethod of claim 11, wherein the minimum quality of service (QoS) isguaranteed by a transport format combination set determined at a radioresource control layer of a UTRAN.
 13. A method for transmitting aplurality of data units within a transmission time interval bymultiplexing data units from a plurality of upper layer channels to alower layer channel, the plurality of upper layer channels each having adifferent transmission priority for transmitting the data units, themethod comprising: determining whether at least one of the plurality ofupper layer channels has an associated minimum quality of service (QoS)requirement; and if at least one of the plurality of upper layerchannels has an associated minimum QoS requirement, selecting atransport format combination from a determined transport formatcombination set such that the minimum QoS for the at least one upperlayer channel is guaranteed.
 14. The method of claim 13, wherein theminimum QoS is guaranteed by the transport format combination setdetermined at a radio resource control layer.
 15. The method of claim13, wherein the minimum QoS is guaranteed by selection of the transportformat combination at a medium access control (MAC) layer.
 16. Themethod of claim 15, further comprising: determining whether any dataunits are to be transmitted over the at least one upper layer channelhaving an associated minimum quality of service (QoS) requirement;wherein the transport format combination is selected by considering theminimum QoS requirement of the at least one upper layer channel beforeconsidering the transmission priority of the plurality of upper layerchannels only if data units are to be transmitted over the at least oneupper layer channel.
 17. The method of claim 13, wherein the pluralityof upper layer channels are logical channels and the lower layer channelis a coded composite transport channel.
 18. The method of claim 13,wherein the multiplexing is performed at the lower layer.
 19. The methodof claim 13, wherein the multiplexing is performed at a medium accesscontrol (MAC) layer.
 20. The method of claim 13, wherein the minimumquality of service (QoS) comprises at least one of a minimum bit rate, aguaranteed bit rate and a minimum transfer delay.
 21. The method ofclaim 13, wherein the plurality of upper layer channels and the lowerlayer channel are in a UTRAN.
 22. The method of claim 13, wherein theplurality of upper layer channels and the lower layer channel are in amobile terminal.
 23. The method of claim 22, wherein the minimum QoS isguaranteed by a transport format combination set determined at a radioresource control layer of a UTRAN.
 24. A mobile communication device fortransmitting a plurality of data units within a transmission timeinterval, the mobile communication device comprising: an RF module; anantenna; a storage unit adapted to store the data and the controlinformation; a display adapted to convey information to the user; and aprocessing unit adapted to select a transport format combination fortransmitting the plurality of data units within a transmission timeinterval by multiplexing data units from a plurality of upper layerchannels to a lower layer channel, the transport format combinationselected from a determined transport format combination set and atransmission priority exists for transmitting the data units from eachof the plurality of upper layer channels, wherein at least one of theplurality of upper layer channels has an associated minimum quality ofservice (QoS) requirement and the transport format combination isselected such that the minimum quality of service (QoS) for the at leastone upper layer channel is guaranteed.
 25. The mobile communicationdevice of claim 24, wherein the plurality of upper layer channels arelogical channels and the lower layer channel is a coded compositetransport channel.
 26. The mobile communication device of claim 24,wherein the transport format combination is selected by considering theminimum quality of service (QoS) requirement of the at least one upperlayer channel before considering the transmission priority of theplurality of upper layer channels.
 27. The mobile communication deviceof claim 24, wherein the multiplexing is performed at the lower layer.28. The mobile communication device of claim 24, wherein themultiplexing is performed at a medium access control (MAC) layer. 29.The mobile communication device of claim 24, wherein the minimum qualityof service (QoS) comprises at least one of a minimum bit rate, aguaranteed bit rate and a minimum transfer delay.
 30. The mobilecommunication device of claim 24, wherein the minimum quality of service(QoS) is guaranteed by the transport format combination set determinedat a radio resource control layer.
 31. The mobile communication deviceof claim 24, wherein the minimum quality of service (QoS) is guaranteedby selection of the transport format combination at a medium accesscontrol (MAC) layer.
 32. The mobile communication device of claim 31,wherein the transport format combination is selected by considering theminimum QoS requirement of the at least one upper layer channel beforeconsidering the transmission priority of the plurality of upper layerchannels only if data units are to be transmitted over the at least onelogical channel.
 33. A network for providing a service to a mobileterminal, the network comprising: a transmitter adapted to transmit dataand a control information indicator to the mobile terminal via a firstchannel and to transmit control information to the mobile terminal via asecond channel; a receiver adapted to receive information from themobile terminal; and a controller adapted to select a transport formatcombination for transmitting a plurality of data units within atransmission time interval by multiplexing data units from a pluralityof upper layer channels to a lower layer channel, the transport formatcombination selected from a determined transport format combination setand a transmission priority exists for transmitting the data units fromeach of the plurality of upper layer channels, wherein at least one ofthe plurality of upper layer channels has an associated minimum qualityof service (QoS) requirement and the transport format combination isselected such that the minimum quality of service (QoS) for the at leastone upper layer channel is guaranteed.
 34. The network of claim 33,wherein the plurality of upper layer channels are logical channels andthe lower layer channel is a coded composite transport channel.
 35. Thenetwork of claim 33, wherein the transport format combination isselected by considering the minimum quality of service (QoS) requirementof the at least one upper layer channel before considering thetransmission priority of the plurality of upper layer channels.
 36. Thenetwork of claim 33, wherein the multiplexing is performed at the lowerlayer.
 37. The network of claim 33, wherein the multiplexing isperformed at a medium access control (MAC) layer.
 38. The network ofclaim 33, wherein the minimum quality of service (QoS) comprises atleast one of a minimum bit rate, a guaranteed bit rate and a minimumtransfer delay.
 39. The network of claim 33, wherein the minimum qualityof service (QoS) is guaranteed by the transport format combination setdetermined at a radio resource control layer.
 40. The network of claim33, wherein the minimum quality of service (QoS) is guaranteed byselection of the transport format combination at a medium access control(MAC) layer.
 41. The network of claim 40, wherein the transport formatcombination is selected by considering the minimum QoS requirement ofthe at least one upper layer channel before considering the transmissionpriority of upper layer channels only if data units are to betransmitted over the at least one logical channel.